Ive got a 700r4. I do not know much on the history of it. It has a nice firm 1-2 shift at about 20mph. It doesn't seem to want to do the 2-3 shift under load. I haven’t driven it far but I can get up to 45 (is the speedo is correct) and it still doesn’t shift while accelerating. If I let off the throttle it shifts. It seems like I read somewhere it should 2-3 shift around 35 - maybe thats wrong. I have not really tried to accelerate beyond the 45 mark - it seems ( by sound - no tach) its revving high and should have shifted by then. I haven't driven anything with a 700r4 in a long time. Maybe with gearing, tire size (perhaps the speedo is off some) its normal and I need to run it out a little further.

Ive done a filter change and its got a corvette servo in it. Id say it shifted about the same with the stock servo. The axles should have 3:73 gears and the tires are About 34” tall.

You need to adjust the throttle valve cable correctly or you will burn it up if you continue it drive it like that. Some people call it the kick down cable which is incorrect. It controls the shift points like a modulator on a TH400 only it is done mechanically.

The TV cable is supposed to ratchet out automatically when you nail the throttle. It may be a good idea to verify actual road speed. It could also be a sticking governor. Or it's just normal for how the trans was built.